Scientists wrapped up their first global census of sea life today, documenting an underwater world that turns out to be livelier and more connected than they thought it would be when they began the project 10 years ago.

The raw numbers behind the $650 million Census of Marine Life are impressive enough: Almost 30 million observations by 2,700 scientists from more than 80 nations spent 9,000 days at sea, producing 2,600 academic papers and documenting 120,000 species for a freely available online database.

Australian marine ecologist Ian Poiner, who chairs the project's steering committee, said the results will serve as a "global baseline" for assessing the state of the ocean's species over the decades to come. "That's not only something that wasn't available in 2000," he told me from London, where the census' final results were shared with the world today. "Many said it was too big a challenge and could not be done."

Kevin Raskoff / Monterey Peninsula College

A new species of hydromedusa, Bathykorus bouilloni, is common below depths of 3,300 feet. Hundreds of Bathykorus bouilloni were observed by a remotely operated vehicle in the Arctic, showing that a new species can be common in a habitat. The species has earned the nickname "Darth Vader jellyfish." Can you see why? Click through our slideshow of weird and wonderful species from the Census of Marine Life.

Scientists are already looking beyond the numbers to flesh out their picture of ocean health. What they found was surprising, said Fred Grassle, director emeritus of Rutgers University's Institute for Marine and Coastal Sciences and Poiner's predecessor as steering committee chair.

"To understand the ocean, you really have to deal with the diversity of species, because the greatest diversity on the planet is in the ocean," he told me. "The majority of that diversity is in the deep parts of the ocean, which have really only begun to be explored by the census."

Poiner said the census showed that life in the oceans is richer than expected, "even in the places some suggested may not have had a richness of life." The thousands upon thousands of species are more connected than expected as well. For example, the "snow" of nutrients that drift down from the ocean's higher levels into the depths play an important role in sustaining deep-sea diversity.

That diversity is under threat in regions ranging from the Mediterranean to the oil-hit Gulf of Mexico, as pointed out in research from the census published two months ago. In some areas of the ocean, up to 90 percent of the species have declined, due to overfishing, pollution and climate change and other ecosystem upsets, Poiner said.

Kevin Raskoff / Monterey Peninsula College

This bizarre new copepod, Ceratonotus steiningeri, was first discovered more than three miles deep in the Angola Basin in 2006. Within a year it was also collected in the southeastern Atlantic and the central Pacific Ocean. Scientists are puzzled about how this tiny animal achieved such widespread distribution, and how it avoided detection for so long. Click through our

"Changes have occurred much earlier than we thought," Poiner told me. "In the few cases where intervention to support recovery has happened, we've found that although change occurs quickly, recovery takes much longer."

Poiner said the census suggests that "a different sort of management is required," based on protecting whole ecosystems rather than individual species.

He and his colleagues are just starting to think about how to follow up on what they've discovered over the past decade. "After 10 years of intensive work, our focus to date has been on ensuring the success of this first census, ensuring that we do have this baseline," he said. "And it's truly been a major accomplishment. But we also have this process to be thinking about what's next."

The process begins this week with a series of meetings in London and is to culminate next September in the Scottish city of Aberdeen, during the World Conference on Marine Biodiversity. The next chapter in the census will draw upon the tools used for this first census, including:

• OBIS: The Ocean Biogeographic Information System is an open-access database documenting the names and locales of 120,000 marine species. In the years to come, fresh observations can be compared with OBIS' baseline data to keep track of the rise and fall of species populations.
• DNA barcoding: Analysis of standard genetic markers can identify which species went where, even on the basis of a single fish scale.
• GEOSS: The Global Earth Observation System of Systems provides a foundation for standardized tracking of marine species by monitoring thousands of electronically tagged "bio-logger" animals, using sonar to look for marine life on the move, and setting up networks of mocrophones to track salmon and the ocean's other migrants. GEOSS is about more than just the oceans: It's an international effort to link together observation systems for a wide spectrum of Earth phenomena, ranging from seismic monitoring networks to satellite imagery databases.
• ARMS: Underwater Autonomous Reef Monitoring Structures, which Poiner compared to "small dollhouses designed in a careful way [to] see what's happening with coral reef diversity," have helped standardize monitoring systems for species in the world's reefs.

One of the census' most eye-opening findings has to do with just how much more is out there still to be found, even after a "decade of discovery." About 250,000 marine species bigger than microbes have been documented to date, but based on an analysis of the discovery rate so far, Poiner said "we know that number will grow to at least a million species, and it's likely to be much higher."

The marine microbial world is an even bigger frontier. The census documented 40,000 genetic sequences from more than 100 microbial families, or phyla, and that's just the start. "There's a richness of microbes out there," Poiner told me. "The estimated kinds of marine microbes could be up to a billion."

So although Poiner, Grassle and their colleagues are in a celebratory mood today, they realize that today's big reveal is just a beginning, and by no means the end of the sea's story.

"All surface life depends on life inside and beneath the oceans," Poiner observed in today's news release. "Sea life provides half of our oxygen and a lot of our food, and regulates climate. We are all citizens of the sea. And while much remains unknown, including at least 750,000 undiscovered species and their roles, we are better acquainted now with our fellow travelers and their vast habitat on this globe."

More wonders of the deep:

• August's highlights from the marine census
• Deep-sea creatures of the Coral Sea
• Marine marvels from Papua New Guinea
• Celebrities of the Celebes Sea
• Aliens lurk in Antarctic depths
• New species from Australia's coral reefs
• Thousands of new species in ocean's depths

Don't miss clicking through our slideshow highlighting some of the weirder and more wonderful species documented by the Census of Marine Life. Among the newly released resources are:

• "First Census of Marine Life 2010: Highlights of a Decade of Discovery," a 64-page summary of the census' work.
• "Discoveries of the Census of Marine Life: Making Ocean Life Count," a 304-page overview of the census' scientific insights and their implications.
• "Life in the World's Oceans: Diversity, Distribution and Abundance," a 384-page summary of findings and discoveries by the 17 census projects.
• "Citizens of the Sea: Wondrous Creatures from the Census of Marine Life," a 216-page coffee-table book providing portraits of about 100 species.
• A National Geographic Society map showing the distribution and travel patterns of ocean species on one side, and the past, present and future of ocean life on the other side.
• New scientific reports added to the Public Library of Science's open-access Collections and Biodiversity Hub.
• A song inspired by the census, titled "Look to the Sea," which will be available for downloading as a music video starting Wednesday.

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